Percutaneous vertebral fusion system

ABSTRACT

A method of repositioning or fixing a first vertebrae or portion of a first vertebrae comprising fixing a bone screw in the first vertebrae and a bone screw in a second vertebrae, where each bone screw has a portal, and inflating an inflatable balloon between the portals, thereby creating a rigid structure between the bone screws.

CROSS-REFERENCE TO RELATED APPLICATION

This Application takes priority from U.S. Provisional Patent ApplicationNo. 60/213,385, filed Jun. 23, 2000 and entitled “Percutaneous InterbodyFusion Device,” the contents of which are incorporated into thisdisclosure by reference in its entirety.

BACKGROUND

The human vertebrae and associated connective elements are subject to avariety of diseases and conditions which cause pain and disability.Among these diseases and conditions are spondylosis, spondylolisthesis,vertebral instability, spinal stenosis and degenerated, herniated, ordegenerated and herniated intervertebral discs. Additionally, thevertebrae and associated connective elements are subject to injuries,including fractures and torn ligaments and surgical manipulations,including laminectomies.

The pain and disability related to these diseases, conditions, injuriesand manipulations often results from the displacement of all or part ofa vertebra from the remainder of the vertebral column. A variety ofmethods have been developed to restore the displaced vertebrae orportions of displaced vertebrae to their normal position and to fix themwithin the vertebral column. For example, open reduction with screwfixation is one currently used method. These methods, however, areassociated with a variety of disadvantages, such as high cost, lengthyinpatient hospital stays and the potential morbidity associated withopen procedures.

Therefore, there is a need for a method of repositioning and fixingdisplaced vertebrae or portions of displaced vertebrae to a positionwithin the vertebral column which is more stable or which causes lessmorbidity. Further, there is a need for a system for performing a methodof repositioning and fixing displaced vertebrae or portions of displacedvertebrae to a position within the vertebral column which is more stableor which causes less morbidity.

SUMMARY

According to one embodiment of the present invention, there is provideda bone screw comprising a proximal portion comprising a head with aproximal end and a portal; a distal portion comprising threads and a tipwith a distal end; and a central lumen configured to receive a guidewireextending coaxially completely through the bone screw from the proximalend to the distal end. The head comprises a proximal portion configuredto mate with the tip of a screwdriver.

According to another embodiment of the present invention, there isprovided a screwdriver comprising a proximal end comprising a handleconfigured to permit grasping of the screwdriver and to permit theapplication of torque to a bone screw; a distal end comprising a shafthaving a tip configured to interface with a bone screw; and a centrallumen configured to receive a guidewire extending coaxially completelythrough the screwdriver from the proximal end to the distal end.

According to yet another embodiment of the present invention, there isprovided an inflatable connection rod comprising a proximal endcomprising a self-sealing valve; a distal end comprising a tip; and acompliant, inflatable balloon between the proximal end and the distalend. The balloon comprises thin, reinforcing wires.

According to another embodiment of the present invention, there isprovided a directing sheath comprising a proximal portion with aproximal end; a distal portion with a distal end; a central portionbetween the proximal portion and the distal portion comprising at leasttwo openings; and a lumen extending through the directing sheath fromthe proximal end to distal end. The directing sheath is preferablyscored along its longitudinal axis to allow the directing sheath to besplit into two separate halves by peeling the directing sheath apart ateither its proximal end or its distal end or both along the scoring.

In a preferred embodiment of the present invention, there is provided amethod of repositioning or fixing one or more unstable, separated ordisplaced vertebrae or one or more portions of one or more vertebrae ina patient's vertebral column. The method comprises:

a) identifying a patient who is a suitable candidate for undergoing themethod;

b) making a stab incision in the patient's skin overlying the patient'svertebral column at or near the level of the vertebrae or portion ofvertebrae to be repositioned or fixed;

c) creating a first tract from the incision to the posterior periostealsurface of the vertebrae;

d) incising the periosteum and extending the first tract into the cortexof the vertebrae;

e) inserting a first guidewire into the first tract;

f) advancing a bone screw comprising a portal and a tip, and ascrewdriver over the first guidewire;

g) applying torque to the bone screw using the screwdriver, therebyfixing part of the tip of the bone screw into the vertebrae while theportal of the bone screw is exterior and dorsal to the vertebrae and theportal is open parallel to the long axis of the vertebral column;

h) removing the screwdriver and the first guidewire;

i) repeating c) through h) for at least one vertebrae which is neitherunstable, separated or displaced and which is adjacent the vertebrae orportion of the vertebrae that is being repositioned or fixed, orrepeating c) through h) for the cranial-ward portion of the sacrum ofthe patient;

j) inserting an inflatable connection rod comprising a proximal end, adistal end and an inflatable balloon between the proximal end and thedistal end, between the portals of the bone screws; and

k) inflating the inflatable balloon thereby creating a rigid structurebetween the inflated inflatable connection rod and the bone screws;

thereby repositioning or fixing the one or more unstable, separated ordisplaced vertebrae or the one or more portions of one or more vertebraeunilaterally.

Identifying a patient who is a suitable candidate comprises identifyinga patient who has one or more unstable vertebrae, one or more portionsof a vertebrae at least partly separated from the remainder of thevertebrae with potential or complete separation, or who has one or morevertebrae or a portion of one or more vertebrae displaced from itsnormal position relative to the vertebral column, or who has one or moreportions of a vertebrae at least partly separated from the remainder ofthe vertebrae and displaced from its normal position relative to thevertebral column; and where the patient has either pain, loss offunction or real or potential instability which is likely due to theseparation or displacement, or separation and displacement.

The method can comprise enlarging the first tract from the incision tothe posterior periosteal surface using a high-pressure fascial dilatorballoon after creating the first tract. Further, inserting an inflatableconnection rod can comprise:

i) percutaneously inserting a hollow needle and advancing the hollowneedle to the portal of one of the bone screws;

ii) introducing a second guidewire through the lumen of the hollowneedle and into the portal of one of the bone screws; and

iii) passing the second guidewire through all of the portals in the bonescrews, thereby creating a second tract.

The method can also comprise:

i) dilating the second tract created by the second guidewire using ahigh pressure balloon;

ii) passing an introducer sheath over the guidewire along the entireguidewire second tract;

iii) removing the guidewire; and

iv) advancing the inflatable connection rod through the introducersheath until the inflatable connection rod advances between the bonescrew portals.

The method can also comprise using a guidewire directing device todirect the advancing second guidewire through at least one bone screwportal, or can comprise using a guidewire capture device to pull thesecond guidewire through the patient's skin. Further, inflating theinflatable balloon can comprise inflating the balloon with a rapidsetting, liquid polymer.

In a particularly preferred embodiment, the method further comprisesrepeating c) through h) for one additional vertebrae, where the oneadditional vertebrae is either unstable, separated or displaced, orwhere one or more portions of the one additional vertebrae is unstable,separated or displaced. In another particularly preferred embodiment,the method further comprises repeating b) through k) on the oppositeside of the spinous processes of the patient's vertebrae column, therebyrepositioning or fixing the one or more unstable, separated or displacedvertebrae or the one or more portions of one or more vertebraebilaterally.

In a preferred embodiment, the method further comprises using adirecting sheath to position the bone screws.

According to another embodiment of the present invention, there isprovided a method of repositioning or fixing a first vertebrae that isunstable, separated or displaced or that has one or more unstable,separated or displaced portions. The method comprises:

a) fixing one or more than one bone screw in the first vertebrae and oneor more than one bone screw in a second vertebrae;

b) inserting an inflatable balloon between the portal of the bone screwin the first vertebrae and the portal of the bone screw in the secondvertebrae; and

c) inflating the inflatable balloon thereby creating a rigid structurebetween the balloon and the bone screws;

thereby repositioning or fixing the first vertebrae or portion of thefirst vertebrae.

In a preferred embodiment, the method further comprises advancing eachbone screw over a guidewire before a). In another preferred embodiment,a) comprises applying torque to each bone screw using a screwdriveradvanced over a guidewire. In another preferred embodiment, c) comprisesinflating the balloon with a rapid setting, liquid polymer.

In a particularly preferred embodiment, the method further comprisesrepeating a) through c) on the opposite side of the spinous processes ofthe patient's vertebrae column, thereby bilaterally repositioning orfixing the one or more unstable, separated or displaced vertebrae or theone or more portions of one or more vertebrae. In a preferredembodiment, the method further comprises using a directing sheath toposition the bone screws before a).

According to.another embodiment of the present invention, there isprovided a kit for repositioning or fixing a first vertebrae that isunstable, separated or displaced or that has one or more unstable,separated or displaced portions. The kit comprises one or more devicesselected from the group consisting of a bone screw according to thepresent invention, a screwdriver according to the present invention, aninflatable connection rod according to the present invention, and adirecting sheath according to the present invention.

FIGURES

These and other features, aspects and advantages of the presentinvention will become better understood from the following description,appended claims, and accompanying figures where:

FIG. 1 shows an elevated perspective view of a bone screw according tothe present invention along the proximal to distal axis;

FIG. 2 shows the bone screw of FIG. 1 rotated ninety degrees around itsproximal to distal axis;

FIG. 3 shows a cutaway, elevated perspective view of the bone screwshown in FIG. 2 along the proximal to distal axis;

FIG. 4 shows another embodiment of the bone screw according to thepresent invention along the proximal to distal axis;

FIG. 5 and FIG. 6 shows elevated perspective views of two screwdriversaccording to the present invention along the proximal to distal axis;

FIG. 7 shows an elevated perspective view of a guidewire directingdevice according to the present invention along the proximal to distalaxis;

FIG. 8 shows an elevated perspective view of an inflatable connectionrod elevated according to the present invention along the proximal todistal axis;

FIG. 9 shows a top perspective view of a directing sheath according tothe present invention along the proximal to distal axis;

FIG. 10 through FIG. 20 show partial cutaway, perspective, midlinesagittal views of a portion of a vertebral column undergoing the methodof the present invention;

FIG. 21 shows a posterior perspective view of a portion of a vertebralcolumn which has had some vertebrae repositioned and fixed bilaterallyaccording to the method of the present invention; and

FIG. 22 through FIG. 24 show a posterior perspective view of a portionof a vertebral column undergoing the method of the present inventionusing a directing sheath according to the present invention.

DESCRIPTION

In one embodiment of the present invention, there is provided a methodof repositioning or fixing one or more unstable, separated or displacedvertebrae or one or more portions of one or more vertebrae such that theone or more unstable, separated or displaced vertebrae or portions aremore stable or are associated with less morbidity. In another preferredembodiment, there is provided a system for performing a method ofrepositioning or fixing one or more unstable, separated or displacedvertebrae or one or more portions of one or more vertebrae such that theone or more unstable, separated or displaced vertebrae or portions areassociated with less morbidity.

The method of the present invention can be used to reposition or fix oneor more unstable, separated or displaced vertebrae or one or moreportions of one or more vertebrae in the cervical, thoracic or lumbarregions of the vertebral column. Additionally, the method can be used toreposition or fix one or more unstable, separated or displaced vertebraeor one or more portions of one or more vertebrae in the lumbar region,using the cranial-ward portion of the sacrum and the “vertebrae” againstwhich the lumbar vertebrae or portion is anchored.

As used in this disclosure, “morbidity” comprises pain, loss offunction, instability and increased tendency to degenerate, as well asother aspects of morbidity, as will be understood by those with skill inthe art with reference to this disclosure.

As used in this disclosure, the term “fixed” with respect to a vertebracomprises stabilizing the vertebra.

As used in this disclosure, the phrase “repositioned or fixed” and itsgrammatical permutations means repositioned, or fixed or bothrepositioned and fixed.

The system of the present invention comprises several devices, some ofwhich will now be disclosed in detail. Referring now to FIG. 1 and FIG.2, there are shown two elevated perspective views of a bone screwaccording to the present invention along the proximal to distal axis,where FIG. 2 shows the bone screw in FIG. 1 rotated ninety degreesaround its proximal to distal axis. Referring now to FIG. 3, there isshown a cutaway, elevated perspective view of the bone screw shown inFIG. 2 along the proximal to distal axis. In one embodiment, the bonescrew is made of a biocompatible material such as titanium or stainlesssteel. In one embodiment, the bone screw has a proximal length to distallength of between about 40 mm and about 60 mm. In a particularlypreferred embodiment, the bone screw has a proximal length to distallength of about 50 mm.

As can be seen, the bone screw 10 comprises a proximal portion 12 with aproximal end 14 and a distal portion 16 with a distal end 18. Theproximal portion 12 comprises a head 20 and a portal 22. In a preferredembodiment, the head 20 comprises a proximal portion 24 configured tomate with the tip of a screwdriver (not shown). In a particularlypreferred embodiment, the top 24 portion comprises a slot. In anotherparticularly preferred embodiment, as shown, the proximal portion 24 isconfigured to mate with a Phillips head screwdriver. Other indentationconfigurations are also suitable, as will be understood by those withskill in the art with reference to this disclosure. For example, asshown in FIG. 4, the proximal portion 24 can comprise a raised platform25 having a plurality of substantially straight sides, such as ahexagonal platform, configured to mate with a corresponding depressionin the distal end of a screwdriver.

The portal 22 of the bone screw extends through the head 20 and ispreferably between about 4 mm and about 8 mm in minimum diameter in theproximal to distal plane and is preferably either oval or round in shapewhen viewed perpendicular to the proximal to distal plane. In aparticularly preferred embodiment, the portal 22 is about 6 mm inminimum diameter in the proximal to distal plane.

The distal portion 16 of the bone screw 10 comprises threads 26 and asharp tip 28. Additionally, the bone screw 10 comprises a central lumen30 extending coaxially completely through the bone screw 10 from theproximal end 14 to the distal end 18 and configured to receive aguidewire used in the present method. Preferably, but not essentially,the bone screw comprises one or more than one perforation 32. The one ormore than one perforation can extend into the central lumen 30, or canextend completely laterally through the distal portion 16. Additionally,the one or more than one perforation 32 can be aligned axially, asshown, or can be staggered axially, not shown. The one or more than oneperforation 32 permits bone to grow into the bone screw 10 and helpstabilize the bone screw 10 within the bone. Additionally, bone matrixmaterial such as a hydroxyapatite preparation can be injected into thecentral lumen 30 and through the one or more than one perforation 32 topromote bone ingrowth.

The system of the present invention further comprises a screwdriverconfigured to apply torque to the bone screw. Referring now to FIG. 5and to FIG. 6, there are shown elevated perspective views of twoembodiments of a screwdriver 40 according to the present invention alongthe proximal to distal axis. As can be seen, the screwdriver comprises aproximal portion 42 comprising a proximal end 44 and a distal portion 46comprising a distal end 48. The proximal portion 42 comprises handles 50configured to permit grasping of the screwdriver and to permit theapplication of torque to a bone screw. Various configurations of theproximal end are possible, as will be understood by those with skill inthe art with reference to this disclosure. Preferably, the handles 50should be able to rotate around their axis independently of each other.

The distal portion 46 of the screwdriver 40 comprises a shaft 52 havinga tip 54 configured to interface with the proximal portion of a bonescrew according to the present invention. Therefore, the configurationof the distal end 48 will depend upon the configuration of the head ofthe bone screws being used in conjunction with the screwdriver 40. Thescrewdriver 40 further comprises a central lumen 55 extending coaxiallycompletely through the screwdriver 40 from the proximal end 44 to thedistal end 48 and configured to receive a guidewire used in the presentmethod.

The system of the present invention can optionally comprise a guidewiredirecting device. Referring now to FIG. 7, there is shown an elevatedperspective view of a guidewire directing device 60 according to thepresent invention along the proximal to distal axis. As can be seen, theguidewire directing device 60 comprises a proximal portion 62 with aproximal end 64 and a distal portion 66 with a distal end 68. Theproximal portion 62 comprises a handle 70. Preferably, the handle 70 isconfigured to assist in grasping and manipulating the handle 70. Thedistal portion 66 comprises a shaft 72 having a fork-tipped end 68. Theguidewire directing device 60 is used to percutaneously alter thedirection of an advancing guidewire by engaging the guidewire in thefork-tipped end 68, rotating the handle and advancing and withdrawingthe handle 70 along the proximal to distal axis, thereby altering thedirection of the advancing guidewire.

The system of the present invention further comprises an inflatableconnection rod. Referring now to FIG. 8, there is shown an elevatedperspective view of an inflatable connection rod according to thepresent invention along the proximal to distal axis in the uninflatedstate. The rod 80 comprises a proximal end 82, a distal end 84 and acompliant, inflatable balloon 86 between the proximal end 82 and thedistal end 84. The proximal end 82 comprises a self-sealing valve 88.The distal end 84 comprises a tip 90, preferably comprising abiocompatible metal. The balloon comprises any suitable material, butpreferably comprises a biocompatible-braided polymer, such as forexample a material selected from the group consisting of nylon,polyethylene and polyurethane. Further preferably, the balloon 86comprises thin, reinforcing metallic wires 92 running the entireproximal to distal length of the lumen of the balloon 86, but separatefrom the balloon wall. The wires 92 increase the tensile strength of theballoon 86 when inflated, as will be understood by those with skill inthe art with reference to this disclosure. The wires 92 preferablycomprise titanium or nitinol, but can comprise another suitable materialas will be understood by those with skill in the art with reference tothis disclosure.

The system of the present invention can optionally comprise a directingsheath that assists in aligning a structure such as a guidewire orinflatable connection rod to pass through the portals in the bone screwsaccording to the present invention. Referring now to FIG. 9, there isshown a top perspective view of a directing sheath according to thepresent invention along the proximal to distal axis. As can be seen, thedirecting sheath 100 comprises a proximal portion 102 with a proximalend (not shown), a distal portion 104 with a distal end (not shown), anda central portion 106 between the proximal portion 102 and the distalportion 106. The central portion 106 comprises at least two openings 108sized substantially the same as the portal on a bone screw according tothe present invention, or slightly larger. The directing sheath 100 hasa lumen 110 extending through its entire length from the proximal end tothe distal end. The lumen 110 is of sufficient internal diameter toallow a structure such as a guidewire or inflatable connection rod topass through the directing sheath between the proximal end and distalend. The directing sheath 100 is scored 112 along its longitudinal axis,on either one line or preferably on two opposing lines, to allow thedirecting sheath 100 to be split into two separate halves by peeling thedirecting sheath 100 apart at either its proximal end or its distal endor both along the scoring 112. The scoring 112 can be partially orcompletely through the sheath wall as will be understood by those withskill in the art with reference to this disclosure.

The directing sheath 100 preferably comprises a biocompatible polymer,though other materials are suitable, as will be understood by those withskill in the art with reference to this disclosure. The directing sheath100 further preferably comprises a radiopaque filament 114 passingaround each opening in the central portion, and more preferably runningthe entire longitudinal length of the directing sheath from the proximalend to the distal end. This filament 114 aids in localizing thedirecting sheath 100 once it has been percutaneously placed.

The method of the present invention involves percutaneously insertingone or more fusion devices into two or more than two adjacent vertebrae,either unilaterally or, preferably bilaterally, where a portion or allof at least one of the vertebrae is unstable, separated or displaced.The fusion devices reposition or fix the displaced vertebra or portionof the displaced vertebra to a position within the vertebral columnwhich is more stable or which causes less morbidity.

Referring now to FIG. 10 through FIG. 19, there are shown a series ofdrawings depicting various stages of the method of repositioning andfixing a displaced vertebra or portion of a displaced vertebra,unilaterally, according to the present invention. FIGS. 9-18 showpartial cutaway, perspective, midline sagittal views of a portion of avertebral column undergoing the method of the present invention.

The method will now be disclosed and depicted with reference to only twovertebrae, one which is either unstable, separated or displaced and oneof which is neither unstable, separated nor displaced. However, themethod can also be applied to three or more vertebrae simultaneously, aswill be understood by those with skill in the art with reference to thisdisclosure. Additionally, the method can be used to stabilize the L5vertebrae, using the cranial-ward portion of the sacrum as the“vertebrae” with which L5 is anchored. Further, though the method isdisclosed and depicted as applied on the left side of the vertebralcolumn, the method can also be applied on the right side of thevertebral column or, preferably, can be applied on both sides of thevertebral column simultaneously, as will be understood by those withskill in the art with reference to this disclosure.

First, the present method comprises identifying a patient who is asuitable candidate for undergoing the method. A suitable candidate hasone or more unstable vertebrae, one or more portions of one or morevertebrae at least partly separated from the remainder of the vertebraewith potential or complete separation, or has one or more vertebrae or aportion of one or more vertebrae displaced from its normal positionrelative to the vertebral column, or has one or more portions of one ormore vertebrae at least partly separated from the remainder of thevertebrae and displaced from its normal position relative to thevertebral column. Further, the suitable candidate will preferably haveeither pain, loss of function or real or potential instability which islikely due to the separation or displacement, or separation anddisplacement. If only a portion of the vertebra is unstable, separatedor displaced, the portion of the vertebra that is unstable, separated ordisplaced will generally include at least part of the vertebral body andadjoining pedicle. However, other unstable, separated or displacedportions of a vertebra can be repositioned or fixed using the presentmethod, as will be understood by those with skill in the art withreference to this disclosure. For example, a suitable patient can have adisease or condition such as spondylosis, spondylolisthesis, vertebralinstability, spinal stenosis and degenerated, herniated, or degeneratedand herniated intervertebral discs, though actual indications requirethe expertise of one of skill in the art as will be understood by thosewith skill in the art with reference to this disclosure.

Next, the present method comprises making a stab incision in thepatient's skin overlying the patient's vertebral column at or near thelevel of the vertebrae or portion of vertebrae to be repositioned orfixed. In a preferred embodiment, the incision is made at or near thelevel of the pedicle of the vertebrae or portion of vertebrae to berepositioned or fixed. The pedicle level is located preferably byidentifying the pedicle shadow using fluoroscopy. In a preferredembodiment, the stab incision is made using a #11 scalpel blade.

Then, as shown in FIG. 10, an 11-gauge bone biopsy needle or itsequivalent is placed through the stab incision to create a tract to theposterior periosteal surface of the vertebrae 200 which is to bestabilized, repositioned or fixed. Next, the biopsy needle 202 is usedto make a small incision in the periosteum and into the cortex of thevertebrae.

Then, as shown in FIG. 11, a rigid, needle-tipped guidewire 204 having aneedle diameter of 13 or 15-gauge is inserted through the biopsy needle202 into the tract, through the periosteal incision and into the cortexof the bone, and the guidewire 204 is advanced into the anterior aspectof the vertebral body 200 or into another suitable portion of thevertebrae 200, as will be understood by those with skill in the art withreference to this disclosure. Insertion of the guidewire 204 ispreferably accomplished using fluoroscopy. This process creates acontinuous tract from the skin surface into the anterior vertebral bodyor suitable portion of the vertebrae 200.

The biopsy needle 202 is then removed and the tract from the skinsurface to the nicked periosteal surface is enlarged by using ahigh-pressure fascial dilator balloon (not shown) over the needle-tippedguidewire. Then, the balloon is removed and a working sheath 206 isintroduced into the dilated tract. Alternately, a metallic sheath with acentral dilator is advanced over the guidewire from the skin surface tothe periosteal surface.

Next, as shown in FIG. 12, a bone screw 208 according to the presentinvention is introduced into the working sheath 206 over the guidewire204 by introducing the central lumen of the bone screw 208 over theproximal end of the guidewire 204. A screwdriver 210 according to thepresent invention is similarly introduced over the guidewire 204. Thebone screw 208 and distal portion of the screwdriver 210 are thenadvanced distally through the sheath 206 and the tract to the periostealsurface of the vertebral 200 until the proximal portion of the bonescrew 208 is engaged by the tip of the screwdriver 210. Torque isapplied to the bone screw 208 using the screwdriver 210 and the bonescrew 208 is advanced until the distal portion of the bone screw 208enters the anterior vertebral body or other suitable portion of thevertebra 200, while the portal of the bone screw 208 is exterior anddorsal to the vertebra 200 and the portal is open parallel to the longaxis of the vertebral column. Then, as shown in FIG. 13, the guidewire204, sheath 206 and screwdriver 210 are removed after satisfactoryplacement of the bone screw 208 has been obtained and confirmed byfluoroscopy. Additionally, bone matrix material such as a hydroxyapatitepreparation can be injected into the central lumen of the bone screw andthrough the one or more than one perforation, if present, to promotebone ingrowth.

The stages disclosed above are repeated for at least one additionalvertebra 212 until each vertebra that is to be repositioned or fixed hasa bone screw 208 applied, and additionally for at least one vertebrawhich is neither unstable, separated nor displaced and which liesadjacent the cranial-most or caudal-most vertebra that is beingrepositioned or fixed. The bone screw 208 placed into the vertebra 212which is neither unstable, separated nor displaced is used as the anchorto reposition or fix each vertebra 200 which is unstable, separated ordisplaced as follows. As will be understood by those with skill in theart with reference to this disclosure, the bone screws can be placedinto the vertebrae in a different order to that described above.

After a bone screw is positioned in each vertebra, the portals areconnected using an inflatable connection rod according to the presentinvention where the rod is inserted between the portals of the bonescrews and inflated to create a rigid structure with the bone screws,thereby repositioning and fixing the one or more than one previouslyunstable, separated or displaced vertebra, or one or more previouslyunstable, separated or displaced portions of one or more vertebrae withthe vertebra that is neither unstable, separated nor displaced.Connection of the bone screws with the inflatable rod is accomplished asfollows.

Referring now to FIG. 14 and FIG. 15, a hollow needle 214, such as a 16gauge or 18 gauge needle, is inserted percutaneously andfluoroscopically advanced to the portal of one of the bone screws 208.While the hollow needle is shown engaging the bone screw 208 in thecranial-ward vertebrae 212, the hollow needle can engage the bone screw208 in the caudalward vertebrae 200 first, as will be understood bythose with skill in the art with reference to this disclosure. FIG. 15is a detailed view of FIG. 14.

Then, as shown in FIG. 16, a needle-tipped, semi-rigid guidewire 216 isintroduced through the lumen of the hollow needle 214 and into theportal of the bone screw 208 in the cranial-ward vertebrae 212. Thehollow needle 214 preferably has a Tuohy needle tip which causes theguidewire 216 to exit the hollow needle 214 perpendicular to thedistal-proximal axis of the bone screw 208, thereby orienting theguidewire 216 perpendicular to the aligned portals in each bone screw208 and parallel to the long axis of the vertebral column. Alternately,the hollow needle 214 can have an angled-tip modified Ross needle orother suitable structure as will be understood by those with skill inthe art with reference to this disclosure.

In a preferred embodiment, as further shown in FIG. 16, a guidewire 218directing device according to the present invention is insertedpercutaneously between the portals of each bone screw 208 and thefork-tipped end is used to direct the advancing guidewire 216 throughthe second bone screw portal, and to reorient the guidewire 216 afterthe guidewire 216 has passed through the portal on the bone screw 208 ofthe caudal-ward vertebrae 212.

In another preferred embodiment, as further shown in FIG. 16, aguidewire capture device 219, such as a snare or grasping forceps, isinserted percutaneously, caudal to the portal of the bone screw in thecaudal-ward vertebrae. The capture device 219 engages the guidewireafter it passes through the portal of the bone screw in the caudal-wardvertebrae and allows the distal end of the guidewire to be pulledthrough the skin posteriorly to obtain control of both the proximal anddistal ends of the guidewire.

In another preferred embodiment, the needle-tipped, semi-rigid guidewire216 comprises an outer helical, flat wire sheath and an innerretractable sharp tip stylet. Once the needle-tipped, semi-rigidguidewire is placed, the stylet can be removed to allow for easiercapture by the capture device with less trauma to the surroundingtissue.

Then, as shown in FIG. 17, the entire guidewire tract is dilated using ahigh pressure balloon and a flexible introducer sheath 220 is passedover the guidewire 216 along the entire guidewire tract exiting thecaudal-ward stab incision. The guidewire 216 is removed after theintroducer sheath 220 is placed.

Next, as shown in FIG. 18, an uninflated, inflatable connection rod 222according to the present invention which is attached to a proximalpushing catheter 224 is advanced through the introducer sheath 220 untilthe inflatable connection rod 222 advances between the two portals andthe proximal end of the inflatable connection rod 222 lies cranial tothe portal on the bone screw 208 in the cranial-ward vertebrae 212 whilethe distal end of the inflatable connection rod 222 lies caudal to theportal on the bone screw 208 in the caudal-ward vertebrae 200. Thesheath 220 is removed and the placement is confirmed by fluoroscopy.

Then, as shown in FIG. 19, the balloon of the inflatable connection rod222 is inflated with a rapid setting, liquid polymer, or its equivalent,and the polymer is allowed to set fixing each bone screw 208 in relationto each other and repositioning and fixing the vertebra 200 or portionof the vertebra that was unstable, separated or displaced. In apreferred embodiment, the liquid polymer is polymethylmethacrylate. Therapid setting, liquid polymer can comprise a light activated polymer andthe method can comprise applying light to promote setting of thepolymer. The inflated balloon of the inflatable connection rod 222expands radially beyond the diameter of the portals of each bone screw208 which helps fix the bone screws 208 in relation to each other.

Finally, as shown in FIG. 20, the pushing catheter 224 is detached fromthe inflatable connection rod 222 by pulling on the pushing catheter 224while holding the inflatable connection rod 222 to disengage theinflatable connection rod 222 from the pushing catheter 224 and thepushing catheter 224 is removed. The inflatable connection rod 222comprises a self-sealing valve which prevents the polymer from leakingonce the pushing catheter is detached. The vertebra is then fixedunilaterally. The method can be repeated on the opposite side of thespinous processes of the patient's vertebrae column, therebyrepositioning or fixing the one or more unstable, separated or displacedvertebrae or the one or more portions of one or more vertebraebilaterally. The stab incisions are closed or sealed as necessary androutine postoperative care administered.

Referring now to FIG. 21, there is shown a posterior perspective view ofa portion of a vertebral column which has had some vertebraerepositioned and fixed bilaterally according to a preferred embodimentof the method of the present invention. When bilateral fixation isaccomplished, it is preferred to place all bone screws before connectingthe portals with inflatable connection rods.

In another embodiment of the present method, a directing sheath 226according to the present invention is advanced over a guidewire untilthe openings in the directing sheath 226 overlie the position in eachvertebra which will receive a bone screw 208. The bone screws 208 arethen placed as disclosed in this disclosure, but through the openings inthe directing sheath 226, which aligns the lumen in the directing sheathwith the portals of the bone screw 208. Then (not shown), a guidewire isthen inserted into the lumen of the directing sheath at the proximal endof the directing sheath and advanced until the guidewire passes througheach portal of the bone screws and exits the body through the lumen ofthe directing sheath at the distal end. The directing sheath is thenremoved by peeling the sheath apart along the scored lines and pullingthe two halves out from the body. The guidewire that was in the lumen ofthe directing sheath remains in place to guide the placement of theuninflated, inflatable connection rod. Alternately, the uninflated,inflatable connection rod can be inserted directly into the lumen of thedirecting sheath at the proximal end and advanced until the uninflated,inflatable connection rod is properly positioned between the portals ofthe bone screws. Referring now to FIG. 22 through FIG. 24, there areshown posterior perspective views of portion of a vertebral columnundergoing the method of the present invention using a directing sheathaccording to the present invention, showing the bone screws placedthrough the openings of the directing sheath. As can be seen in FIG. 22,the directing sheath 300 is positioned adjacent the vertebral column 302according to the present invention. Next as can be seen in FIG. 23,guidewires 304 are used to place bone screws 306 through openings 308 inthe directing sheath 300. Finally as can be seen in FIG. 24, thedirecting sheath 300 is removed by the directing sheath 300 into twoseparate halves.

In a preferred embodiment, there is provided a kit for performing themethod of the present invention. The kit comprises a plurality of bonescrews according to the present invention. The kit can also compriseother components of the system of the present invention, such as aguidewire directing device, an inflatable connection rod and a directingsheath. In another preferred embodiment, the kit also comprises ascrewdriver according to the present invention.

Although the present invention has been discussed in considerable detailwith reference to certain preferred embodiments, other embodiments arepossible. Therefore, the scope of the appended claims should not belimited to the description of preferred embodiments contained in thisdisclosure.

I claim:
 1. A method of repositioning or fixing one or more unstable,separated or displaced vertebrae or one or more portions of one or morevertebrae in a patient's vertebral column, the method comprising: (a)identifying a patient who is a suitable candidate for undergoing themethod; (b) making a stab incision in the patient's skin overlying thepatient's vertebral column at or near the level of the vertebrae orportion of vertebrae to be repositioned or fixed; (c) creating a firsttract from the incision to the posterior periosteal surface of thevertebrae; (d) incising the periosteum and extending the first tractinto the cortex of the vertebrae; (e) inserting a first guidewire intothe first tract; (f) advancing a bone screw comprising a portal and atip, and screwdriver over the first guidewire; (g) applying torque tothe bone screw using the screwdriver, thereby fixing part of the tip ofthe bone screw into the vertebrae while the portal of the bone screw isexterior and dorsal to the vertebrae and the portal is open parallel tothe long axis of the vertebrae column; (h) removing the screwdriver andthe first guidewire; (i) repeating (c) through (h) for at least onevertebrae which is neither unstable, separated or displaced and which isadjacent to the vertebrae or portion of the vertebrae that is beingrepositioned or fixed, or repeating (c) through (h) for the cranial-wardportion of the sacrum of the patient; (j) inserting an inflatableconnection rod comprising a proximal end, a distal end and an inflatableballoon between the proximal end and the distal end, between the portalsof the bone screws; and (k) inflating the inflatable balloon therebycreating a rigid structure between the inflated inflatable connectionrod and the bone screws; thereby repositioning or fixing the one or moreunstable, separated or displaced vertebrae or the one or more portionsof one or more vertebrae unilaterally.
 2. The method of claim 1, whereidentifying a patient who is a suitable candidate comprises identifyinga patient who has one or more unstable vertebrae, one or more portionsof a vertebrae at least partly separated from the remainder of thevertebrae with potential or complete separation, or who has one or morevertebrae or a portion of one or more vertebrae displaced from itsnormal position relative to the vertebrae column, or who has one or moreportions of a vertebrae at least partly separated from the remainder ofthe vertebrae and displaced from its normal position relative to thevertebrae column; and where the patient has either pain, loss offunction or real or potential instability which is likely due to theseparation or displacement, or separation and displacement.
 3. Themethod of claim 1, further comprising enlarging the first tract from theincision to the posterior periosteal surface using a high-pressurefascial dilator balloon after creating the first tract.
 4. The method ofclaim 1, where inserting an inflatable connection rod comprises: (i)percutaneously inserting a hollow needle and advancing the hollow needleto the portal of one of the bone screws; (ii) introducing a secondguidewire through the lumen of the hollow needle and into the portal ofone of the bone screws; and (iii) passing the second guidewire throughall of the portals in the bone screws, thereby creating a second tract.5. The method of claim 4, further comprising: (i) dilating the secondtract created by the second guidewire using a high pressure balloon;(ii) passing an introducer sheath over the guidewire along the entireguidewire second tract; (iii) removing the guidewire; and (iv) advancingthe inflatable connection rod through the introducer sheath until theinflatable connection rod advances between the bone screw portals. 6.The method of claim 4, further comprising using a guidewire directingdevice to direct the advancing second guidewire through at least onebone screw portal.
 7. The method of claim 4, further comprising using aguidewire capture device to pull the second guidewire through thepatient's skin.
 8. The method of claim 1, where inflating the inflatableballoon comprises inflating the balloon with a rapid setting, liquidpolymer.
 9. The method of claim 8, where the liquid polymer is lightactivated polymer.
 10. The method of claim 8, further comprisingrepeating (c) through (h) for one additional vertebrae, where the oneadditional vertebrae is either unstable, separated or displaced, orwhere one ore more portions of the one additional vertebrae is unstable,separated or displaced.
 11. The method of claim 1, further comprisingrepeating (b) through (k) on the opposite side of the spinous processesof the patient's vertebrae column, thereby repositioning or fixing theone or more unstable, separated or displaced vertebrae or the one ormore portions of one or more vertebrae bilaterally.
 12. The method ofclaim 1, further comprising using a directing sheath to position thebone screws.
 13. The method of claim 1, where the bone screw comprises acentral lumen and where the method further comprises injecting bonematrix material into the central lumen.
 14. A method of repositioning orfixing a first vertebrae that is unstable, separated or displaced orthat has one or more unstable, separated or displaced portions, themethod comprising: (a) fixing one or more than one bone screw in thefirst vertebrae and one or more than one bone screw in a secondvertebrae; (b) inserting an inflatable balloon between the portal of thebone screw in the first vertebrae and the portal of the bone screw inthe second vertebrae; and (c) inflating the inflatable balloon therebycreating a rigid structure between the balloon and the bone screws;thereby repositioning or fixing the first vertebrae or portion of thefirst vertebrae.
 15. The method of claim 14, further comprisingadvancing each bone screw over a guidewire before (a).
 16. The method ofclaim 14, where (a) comprises applying torque to each bone screw using ascrewdriver advanced over a guidewire.
 17. The method of claim 14, where(c) comprises inflating the balloon with a rapid setting, liquidpolymer.
 18. The method of claim 14, further comprising repeating (a)through (c) on the opposite side of the spinous processes of thepatient's vertebrae column, thereby bilaterally repositioning or fixingthe one or more unstable, separated or displaced vertebrae or the one ormore portions of one or more vertebrae.
 19. The method of claim 14,further comprising using a directing sheath to position the bone screwsbefore (a).
 20. A method of repositioning or fixing a first vertebraethat is unstable, separated or displaced or that has one or moreunstable, separated or displaced portions, the method comprising: fixinga first bone screw having a portal in the first vertebrae; fixing asecond bone screw having a portal in a second vertebrae; and inserting aguidewire through a tissue tract and through the portal of the firstbone screw in the first vertebrae and through the portal of the secondbone screw in the second vertebrae.
 21. The method of claim 20, furthercomprising advancing each bone screw over a guidewire before the bonescrew is fixed in a vertebrae.
 22. The method of claim 20, whereinfixing each bone screw comprises applying torque to each bone screwusing a driver advanced over a guidewire.
 23. The method of claim 20,further comprising inserting an inflatable balloon between the portal ofthe first bone screw in the first vertebrae and the portal of the secondbone screw in the second vertebrae.
 24. The method of claim 23, furthercomprising inflating the inflatable balloon.
 25. A method ofrepositioning or fixing one or more unstable, separated or displacedvertebrae or one or more portions of one or more vertebrae in apatient's vertebral column, the method comprising: identifying a patientwho is a suitable candidate for undergoing the method; making a stabincision in the patient's skin overlying the patient's vertebral columnat or near the level of the vertebrae or portion of vertebrae to berepositioned or fixed; creating a first tract from the incision to theposterior periosteal surface of the vertebrae; incising the periosteumand extending the first tract into the cortex of the vertebrae;inserting a first guidewire into the first tract; advancing a bone screwcomprising a portal and a tip, and a driver over the first guidewire;applying torque to the bone screw using the driver, thereby fixing partof the tip of the bone screw into the vertebrae while the portal of thebone screw is exterior and dorsal to the vertebrae and the portal isopen parallel to the long axis of the vertebrae column; removing thedriver and the first guidewire; repeating (c) through (h) for at leastone vertebrae which is neither unstable, separated or displaced andwhich is adjacent to the vertebrae or portion of the vertebrae that isbeing repositioned or fixed, or repeating (c) through (h) for thecranial-ward portion of the sacrum of the patient; and inserting aguidewire between the portals of the bone screws.
 26. A method ofrepositioning or fixing a first vertebrae that is unstable, separated ordisplaced or that has one or more unstable, separated or displacedportions, the method comprising: fixing a first bone screw having aportal in the first vertebrae; fixing a second bone screw having aportal in a second vertebrae; inserting an inflatable balloon throughthe portal of the first bone screw in the first vertebrae and throughthe portal of the second bone screw in the second vertebrae; andinflating the balloon.
 27. The method of claim 23, additionallycomprising inflating the inflatable balloon by introducing a curablemedia into the inflatable balloon.
 28. The method of claim 23,additional comprising inflating the inflatable balloon by introducing arapid setting, liquid polymer into the inflatable balloon.
 29. Themethod of claim 20, wherein the first and second vertebrae are adjacenteach other.
 30. The method of claim 20, wherein the method isaccomplished percutaneously.
 31. The methods of claim 20, additionallycomprising the step of advancing an implant through the portal in thefirst bone screw and the portal in the second bone screw.
 32. The methodof claim 26, wherein inflating the inflatable balloon comprisesintroducing a curable media into the inflatable balloon.
 33. The methodof claim 26, wherein inflating the inflatable balloon comprisesintroducing a rapid setting, liquid polymer into the inflatable balloon.34. The method of claim 26, wherein the first and second vertebrae areadjacent each other.
 35. The method of claim 26, wherein the method isaccomplished percutaneously.